Comparing oxygen moles in combustion reactions

Steps:

• Identify the balanced combustion equation for each element: general form is element + O₂ → oxide.
• Calculate moles of O₂ per mole of element from the coefficient in the balanced equation.
• Compare the O₂ coefficients: lower value means least moles required.
• Select the element with the smallest O₂ coefficient.

Why D is correct:

• Element D forms an oxide requiring only 0.5 moles of O₂ per mole of element, per the stoichiometry of its combustion reaction (e.g., 2D + O₂ → 2DO).

Why the others are wrong:

• A requires 1 mole of O₂ per mole, higher than D's 0.5.
• B requires 1.5 moles of O₂ per mole, higher than D's 0.5.
• C requires 2 moles of O₂ per mole, higher than D's 0.5.

Final answer: D